1. Statement of the Technical Field
The present invention relates to the field of message broadcasting and more particularly close range broadcasting of messages to localized receivers.
2. Description of the Related Art
Many accidents and fatalities occur annually in consequence of motorists who remain oblivious to developing and existing road hazards which are encountered in the route of the motorists. Examples include passing emergency vehicles such as fire trucks, ambulances and police cruisers, parked vehicles in the roadway such as police cruisers who have executed a traffic stop or buses into which and from which passengers have entered and exited, respectively, unexpected train crossings, obscured construction sites, stopping buses and other such vehicles and the like. In those circumstances where a passing motorist remains unaware of a road hazard, particularly in those cases where the roadway environment lacks visibility, the motorist will fall victim to the hazard, resulting either in injury to the motorist, a nearby pedestrian, or other motorists in the vicinity of the road hazard.
Recognizing the need to alert motorists of approaching danger, several mechanisms and processes have been implemented to prevent resulting harm. Specifically, emergency vehicles have long utilized noise making and visual attention getting devices such as sirens to alert nearby motorists of an approaching emergency vehicle-even where the motorist may be audibly distracted through the operation of a car stereo. Similarly, for nearly a decade selected radar detectors in combination with specialized transmitters have been configured to report the proximity of construction activity through the radar detectors. Finally, buses and other large vehicles have been retrofitted in the past with visual signs which alert following motorists to the impending stoppage of the bus or vehicle.
Nevertheless, the use of sirens and visual signs alone cannot prove effective for those motorists where are not within earshot or sight of the road hazard. To that end, several have developed road hazard advance notification systems. For instance, U.S. Pat. No. 6,411,891 B1 issued on Jun. 25, 2002 to Jones and assigned to Global Research Systems, Inc. teaches an advance notification system which can notify users of the impending arrival of a transportation vehicle, for instance a school bus. The system can include each of a vehicle control unit, a base station, and any number of receiving devices, such as a pager, television, mobile phone, or office phone. As Jones requires subscribers to request notification of a particular vehicle, however, Jones fails to directly address the problem at hand. Hence, the Jones teachings cannot be applied to the problem of the unanticipated approach of a vehicle.
U.S. Pat. No. 5,889,475 issued on Mar. 30, 1999 to Klosinski et al. more directly addresses the problem of detecting approaching road hazardsxe2x80x94specifically emergency vehicles. In the Klosinski specification, a fixed traffic control device, such as a traffic signal can be programmed to detect an approaching emergency vehicle. Specifically, a transmitter in the approaching emergency vehicle can transmit an alert to the traffic signal as the vehicle approaches the traffic signal. Responsive to receiving the alert, the traffic signal can emit an audible and visual indication of the oncoming emergency vehicle.
In addition to transmitting the alert to the traffic signal, the transmitter can broadcast a xe2x80x9csirenxe2x80x9d over AM and FM frequencies at short range so as to override the programming received at those frequencies in the AM and FM receivers disposed in nearby vehicles. In this way, motorists whose use of their respective radio receivers would otherwise inhibit the detection of the traffic signal siren, will be able to hear the siren broadcast through their respective radio receivers. Still, the Klosinski technology cannot effectively provide alert data other than a siren. Consequently, the use of the Klosinski technology alone cannot facilitate motorists for determining the nature and magnitude of the approaching road hazard.
Specifically, upon detecting the siren through a radio receiver, a motorist would not be able to determine whether the alert has arisen from the presence of an emergency vehicle, a stopping bus, or a construction site. While the approach of an emergency vehicle would require that the motorist pull to the side of the roadway as quickly as possible, the approach of a construction site would only require a heightened level of awareness on behalf of the motorist. To pull immediately to the side of the roadway upon detecting an approaching construction site not only would prove counterproductive and reactionary, but also dangerous. Thus, the use of the Klosinski technology can exacerbate the problem at hand as a motorist could conceivable overreact to every siren audibly detected through the radio receiver of the motorist.
U.S. Pat. No. 6,160,493 issued on Dec. 12, 2000 to Smith and assigned to Estech Corporation addresses the deficiencies of Klosinski to the extent that Smith teaches a radio warning system for hazard avoidance which has been configured to identify the source of the hazard within alerts broadcast to radio receivers in proximate vehicles. More particularly, in the Smith disclosure, unique identification information concerning the potentially hazardous condition can be included in the broadcast alert signal. The information specifically can include whether the transmitter has been deployed in an emergency vehicle, school bus, train, construction vehicle, mail or package delivery vehicle or other transport carrier capable of collision.
Nevertheless the Smith technology does not address the need for motorists to understand the exact nature of a road hazard. For instance, while it can be helpful to receive data which generically describes the vehicle involved in a collision, in most cases the skilled artisan would prefer that the motorists which are proximate to a road hazard receive explicit instructions and information regarding a recommended course of action to be performed in response to the approaching road hazard. As the Smith technology can only provide pre-programmed data through a transmitter regarding the type of vehicle approaching the receiver, the Smith technology cannot so provide explicit instructions regarding a recommended course of action to the receiver.
U.S. Pat. No. 4,764,978 issued on Aug. 16, 1988 to Argo et al. for EMERGENCY VEHICLE RADIO TRANSMISSION SYSTEM differs from the Smith technology as the Argo technology can include either or both of an audio tape playback device and a microphone so that real-time information regarding a road hazard can be broadcast to motorists over a broad band of AM and FM frequencies. Specifically, the Argo system is an indicative radio broadcasting system which, through an array of multiple signal filters, signal oscillators, antenna matching blocks, and a multiplicity of inductors, tape recorded messages can be broadcast over a set of FM frequencies so that proximate motorists can receive the recorded message regardless of the FM frequency to which the motorists are tuned.
Notwithstanding the foregoing, the Argo technology as a dated technology suffers from the inherent deficiencies of an analog era. For example, as the Argo technology is an inductive broadcasting system, incorporated high-frequency filters and oscillators constantly must be tuned. Moreover, the Argo design cannot comply with the United States Federal Communications Commission (FCC) requirement that channels must remain separated and silence must exist between channels on the FM band. For example, the Argo technology transmits an audio alert message even between FM channels and at full power, thus obliterating the FCC silence requirement, and possibly preventing modern phase lock loop (PLL) receivers from locking on a particular signal. Additionally, the full power approach of Argo also can reduce the range of transmission and can distort the audio quality.
The Argo system also requires the use of an analog tape playback device to provide alert messages to nearby motorists. First, as analog tape playback mechanisms are primarily mechanical in nature, the Argo technology cannot easily be deployed in extreme environments where excessive vibrations are the norm, such as in emergency vehicles. Second, analog tape playback mechanisms are limited in terms of recording and playing back customized messages, and more particularly in selecting individual messages for playback which have pre-recorded in a single audio tape. The selection of a message from among several messages in an analog audio tape can be both time consuming and difficultxe2x80x94especially through the use of fast-forward and fast-rewind operations. Thus, selecting a particular recorded message in the Argo system could prove complicated and dangerous for the operator of an emergency vehicle. Finally, the use of an analog tape playback mechanism necessarily implies required maintenance which, in the absence thereof, could result in playback failure.
A careful review of the prior art will indicate to one of ordinary skill in the art that present systems for broadcasting road hazard alerts across the FM frequency spectrum remains deficient in several aspects. For example, it can be difficult to deploy analog based systems in the harsh environment of emergency vehicles. Second, the strict requirements of the FCC mandate particular broadcasting techniques not presently satisfied by existing systems. Third, conventional emergency broadcasting systems fail to provide flexibility in the type and content of alert messages provided to nearby motorists. Finally, conventional emergency broadcasting systems cannot be adapted to provide alerts based on events other than approaching road hazards, such as so-called xe2x80x9cAmber Alertsxe2x80x9d, terrorist warnings, and general information dissemination practices.
The present invention is a selective message broadcasting system which overcomes the deficiencies of the referenced art. In particular, unlike convention emergency vehicle alert broadcasting systems, in the message broadcasting system of the present invention, a multiplicity of messages can be pre-recorded and digitally retrieved on command as the occasion arises. Furthermore, messages can be recorded on an ad-hoc basis. Significantly, a selected message can be broadcast to a set of transmission channels in a particular broadcast spectrum while maintaining the required silence intervals between each transmission channel. Thus, unlike conventional attempts to provide a comprehensive alert messaging system, the present invention can satisfy the requirements of the United States FCC.
A selective message broadcasting system which has been configured in accordance with the present invention can include fixed storage configured to store a plurality of pre-recorded audio messages. A digital audio system can be coupled to the fixed storage, the digital audio system including playback logic for playing back selected ones of the pre-recorded audio messages stored in the fixed storage. A center frequency modulator can be coupled to the digital audio system and the modulator can be configured to modulate the selected ones of the pre-recorded audio messages about a center frequency in a particular broadcast spectrum. Finally, a frequency band comb distributor can be coupled to the center frequency modulator and configured to replicate the modulated selected ones of the pre-recorded audio messages across a set of frequency transmission channels in the particular broadcast spectrum while maintaining a silence interval between each of the frequency transmission channels in the particular broadcast spectrum. Notably, the broadcast spectrum can include the FM spectrum and the AM spectrum.
A method of selectively broadcasting messages from a broadcast transmitter across a multiplicity of frequency transmission channels to receivers in short range of the transmitter can include several steps. First, one of a set of pre-recorded messages stored in fixed storage can be selected in the transmitter. The selected one of the set of pre-recorded messages can be played back. Subsequently, the digitally played back message can be modulated about a center frequency in a particular broadcast spectrum. Importantly, the modulated message can be replicated across a selection of broadcast transmission channels in the particular broadcast spectrum while maintaining silence intervals in between each one of the broadcast transmission channels. Finally, the replications can be amplified and the amplication can be transmitted to the receivers in short range of the transmitter.